Interpretive Summary: Chicken carcasses are dipped into hot water communal baths during the initial phase of processing to loosen the feathers for removal by automatic picking machines. Prior research has shown that these hot water baths can allow harmful bacteria to move from one carcass to another increasing health risk to consumers. The objective of this project was to compare subcutaneous temperatures of the communal bath and spray scalded carcasses to determine the feasibility of eliminating the communal baths. Thermocouples positioned beneath the skin of carcasses at 8 locations provided data for a subcutaneous temperature profile of carcasses, comparing immersion and spray scalding methods as well as different scalding temperatures. Spray scalding overall demonstrated less variation and a closer grouping of the final temperatures, but required higher water temperatures to produce subcutaneous temperatures similar to the immersion scalder. Additional carcasses were scalded, picked, and examined for skin appearance and picking efficiency. All carcasses, spray scalded had a cooked appearance when evaluated, therefore spray scald times were reduced to provide a comparable carcass quality. The data from this research demonstrates that the feasibility for spray scalding exists but more work is needed to develop an alternative scalding system for the poultry industry that can reduce the risk of harmful bacteria reaching the consumer.

Technical Abstract:
To compare immersion and spray scalding temperature profiles, thermocouples were positioned beneath the skin of broiler carcasses in eight separate locations. The locations were as follows: 1 and 2) the upper left and right breast, 3 and 4) middle of the left and right thigh, 5 and 6) beneath the left and right wing, 7) the lower back above the pygostyle, and 8) the upper back between the wings. Standard immersion scalding at 52 or 56.5 C for two min or a proto-type spray scalder at 60, 65, or 70 C for one min were used to monitor subcutaneous temperature during scalding. Immersion scalding resulted in an exponential type profile with the lower temperature having less temperature deviation for the monitored locations. Among sampling locations, the spray scald temperatures were divergent among locations and the highest temperatures were recorded when thermocouples were within the spray patterns. As with the immersion scalded carcasses, lower temperatures for the spray scalding demonstrated less deviation among the monitored locations and a closer grouping of the final temperatures. The only spray scald temperature tested where subcutaneous temperatures approached those of the immersion scalded carcasses was at 70 C. Additional carcasses were scalded, picked, and examined for skin appearance and picking efficiency. All carcasses spray scalded for 60 s had a "cooked appearance" when evaluated. When spray scald times were reduced to 30 s, skin appearance improved, but with the exception of the 70 C trial, picking efficiency was poorer.